Franck-Hertz Apparatus

Franck-Hertz Apparatus

Franck-Hertz Apparatus, complete with DC Current Amplifier and Power Supplies I and II.

Products

2674239

SE-9639

Franck-Hertz Apparatus

Franck-Hertz Apparatus

SE-9639
- Get Quote

Stand-alone system for fundamental constants classic demonstrations, can also be used with the 850 Interface and PASCO Capstone software.

Also Available:

2633332

SE-9650

Franck-Hertz Tube Enclosure with Ar Tube

Franck-Hertz Tube Enclosure with Ar Tube

SE-9650
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2688561

SE-9645

Franck-Hertz Argon Tube

Franck-Hertz Argon Tube

SE-9645
- Get Quote

Replacement Argon Tube for PASCO's Franck-Hertz Apparatus.

Overview

Electrons are accelerated by applying a known potential between two grids inside the argon tube. When an electron has sufficient kinetic energy to excite one of argon’s outer orbital electrons and has an inelastic collision with an argon atom, the electron loses a specific amount of kinetic energy. This loss of electron kinetic energy causes a decrease in the electron current in the argon tube. The excited argon electron will within a very short time fall from the excited state back into the ground state level, emitting energy in the form of photons.

As the accelerating voltage is increased, the electrons undergo multiple collisions and the excitation energy of the argon atom can be determined by the differences between the accelerating voltages that cause a decrease in the current. Planck‘s constant can be determined.

How It Works

As early as 1914, James Frank and Gustav Hertz discovered in the course of their investigations an energy loss in distinct steps for electrons passing through mercury vapor and a corresponding emission at the ultraviolet line (λ= 254 nm) of mercury. They performed this experiment that has become one of the classic demonstrations of the quantization of atomic energy levels. They were awarded the Nobel Prize for this work in 1925.